Spring-Cloud系列 Feign (三)

什么是Feign？

    Feign是一个声明式Web服务客户端。支持可插拔编码器和解码器。Spring Cloud的Feign添加了对Spring MVC注释的支持，并且使用了Spring Web中默认使用的相同HttpMessageConverters。Spring Cloud的Feign将Ribbon和Eureka集成在一起，在使用Feign时提供负载均衡的http客户端。

快速开始

这个案例依赖Eureka-Server,请准备好server服务。Eureka相关查看Spring-Cloud系列(一) Eureka

添加依赖

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.13.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <spring-cloud.version>Dalston.SR5</spring-cloud.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-feign</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

代码

注解扫描

@EnableEurekaClient
@EnableFeignClients
@SpringBootApplication
public class FeignApplication {

    public static void main(String[] args) {
        SpringApplication.run(FeignApplication.class, args);
    }
}

定义客户端

@FeignClient("eureka-client-one") //必须是你调用服务的名称,即spring.application.name
public interface FeignTestClient {

    /**
     * Feign默认解析合约是Spring-MVC的注解
     * @return
     */
    @RequestMapping(method = RequestMethod.GET, value = "/url")
    String getUrl();
}

使用

@Autowired
private FeignTestClient feignTestClient;

@GetMapping("/test")
public String testService(){
    return feignTestClient.getUrl();
}

application配置

server:
</br>  port: 8083
</br>spring:
</br>  application:
</br>    name: feign-one
</br>eureka:

</br>  instance:
</br>    prefer-ip-address: true
</br>    instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}}
</br>  client:
</br>    serviceUrl:
</br>      defaultZone: http://user:Pass123456@localhost:8761/eureka

启动效果

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自定义feignClient和feign日志登等级

配置定义客户端

自定义配置

@Configuration
public class FeignConfiguration {
    
    @Bean
    public Contract feignContract() {
        return new feign.Contract.Default();
    }
}

定义客户端

@FeignClient(name = "eureka-client-one",configuration = FeignConfiguration.class) 
public interface FeignTestClient {
    @RequestLine("GET /url") //根据配置现在Feign支持的是原生注解
    String getUrl();
}

  注意！Feign的客户端的自定义和Ribbon类似，配置类不能放在启动类的平级和子目录下。否则会覆盖全局配置，正确目录如下:</br>

目录结构

代码定义客户端

定义客户端

public interface FeignTestClient {
    @RequestLine("GET /url")
    String getUrl();
}

使用客户端

@RestController
@Import(FeignClientsConfiguration.class)
public class FeignTestContoller {

    @GetMapping("/test")
    public String testService(){
        FeignTestClient feignTestClient = Feign.builder()
                .options(new Request.Options(1000, 3500))
                .retryer(new Retryer.Default(5000, 5000, 3))
                .requestInterceptor(new BasicAuthRequestInterceptor("user", "Pass123456"))
                .target(FeignTestClient.class, "http://lodalhost:8080");
        return feignTestClient.getUrl();
    }
}

Feign提供的配置

    Feign提供以下默认配置：

• Decoder feignDecoder: ResponseEntityDecoder (which wraps a SpringDecoder)
• Encoder feignEncoder: SpringEncoder
• Logger feignLogger: Slf4jLogger
• Contract feignContract: SpringMvcContract
• Feign.Builder feignBuilder: HystrixFeign.Builder
• Client feignClient: if Ribbon is enabled it is a LoadBalancerFeignClient, otherwise the default feign client is used.

    Feign未提供默认配置：

• Logger.Level
• Retryer
• ErrorDecoder
• Request.Options
• Collection<RequestInterceptor>
• SetterFactory

自定义日志级别

application配置

logging:
</br>  level:
</br>    com.midai.feign.client.FeignTestClient: DEBUG #Client是用户自定义Clien全称

代码配置

@Configuration
public class FeignConfiguration {
    @Bean
    Logger.Level feignLoggerLevel() {
        return Logger.Level.FULL;
    }
}

Feign的可选日志等级

• NONE, No logging (DEFAULT).
• BASIC, Log only the request method and URL and the response status code and execution time.
• HEADERS, Log the basic information along with request and response headers.
• FULL, Log the headers, body, and metadata for both requests and responses.

Feign其他用法和配置

抽取公用包依赖

UserService.java

public interface UserService {
    @RequestMapping(method = RequestMethod.GET, value ="/users/{id}")
    User getUser(@PathVariable("id") long id);
}

UserResource.java

@RestController
public class UserResource implements UserService {
}

UserClient.java

@FeignClient("users")
public interface UserClient extends UserService {
}

    接口抽取共用，服务提供方直接实现,FeignClient继承提高代码可用性。

Feign请求响应设置

Feign请求响应压缩

feign:
</br>  compression:
</br>    request:
</br>      enabled： true
</br>feign:

</br>  compression:
</br>    response:
</br>      enabled: true

Feign请求设置

feign:

</br>  compression:
</br>    request:
</br>      mime-types: text/xml,application/xml,application/json
</br>feign:
</br>  compression:
</br>    request:
</br>      min-request-size: 2048

    本文参考Spring-Cloud-Feign，Feign-Builder用法